US11906029B2 - Continuously variable transmission engine braking system - Google Patents

Abstract

A drive sheave assembly of a continuously variable transmission is provided. A fixed sheave of the assembly includes a central recess. A plurality of sheave ramps are located within the central recess. A one-way engagement collar is configured to rotate freely on an end portion of a sleeve when the sleeve rotates in a first direction and lock onto rotation of the sleeve when the sleeve rotates in a second direction. The one-way engagement collar further has a plurality of ramp pockets. A ramp member is received within each ramp pocket of the plurality of ramp pockets in the one-way engagement collar. Each ramp member is configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of a belt when the sleeve rotates in the second direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to U.S. Provisional Application Ser. No. 63/133,498, same title herewith, filed on Jan. 4, 2021, and to U.S. Provisional Application Ser. No. 63/225,688, same title herewith, filed on Jul. 26, 2021, which both are incorporated in their entirety herein by reference.

BACKGROUND

Continuously variable transmissions (CVTs) provide a transmission system that automatically adjusts its gearing as needed. A typical CVT includes a drive sheave assembly and a driven sheave assembly. The drive sheave assembly is in operational communication with an engine and the driven sheave assembly is in operation a communication with a drivetrain of a vehicle. A belt provides operational communication between the drive sheave assembly and the driven sheave assembly. Each sheave assembly typically includes a fixed sheave and a movable sheave that are mounted on a post. A movable sheave activation assembly moves the movable sheave in relation to the fixed sheave to adjust a location of the belt in relation to a central axis of the sheave assembly to change the gearing by selectively causing the belt to ride up and down on engagement surfaces of the fixed and moveable sheaves.

Engine braking is a desired feature to help slow down a vehicle in certain situations. For example, if a vehicle is traveling down a steep hill, traditional braking systems to slow the vehicle may not be adequate. Engine braking is expressly desired in vehicles that are subject to extreme terrain such as, but not limited to, all-terrain vehicles (ATVs) and utility terrain vehicles (UTVs). Providing an engine braking system that includes a CVT can be a challenge since, during a typical engine braking situation, the fixed sheave and the moveable sheave of the drive sheave assembly are spaced away from each other with only an inner surface of the belt engaging a sleeve that is free to rotate on the post (to achieve an idle condition). A reliable efficient engine braking system for a CVT is desired. Further, it may be desired to have an engine braking system in a CVT that disengages when a certain threshold is reached to protect vehicle components.

SUMMARY OF INVENTION

The following summary is made by way of example and not by way of limitation. It is merely provided to aid the reader in understanding some of the aspects of the subject matter described. Embodiments provide a drive sheave assembly with an engine braking feature that includes a one-way engagement collar that is selectively received within a central recess of a fixed sheave.

In one embodiment, a drive sheave assembly of a continuously variable transmission is provided. The drive sheave assembly includes a post, a fixed sheave, a movable sheave, a sleeve, a one-way engagement collar and ramp members. The fixed sheave is statically mounted on the fixed post and includes a central recess. The fixed sheave further includes a plurality of sheave ramps within the central recess. The movable sheave is slidably mounted on the fixed post. The sleeve is rotatably mounted on the post. A mid-portion of the sleeve is positioned between the fixed sheave and the movable sheave and has an outer surface configured to engage an inner surface of a belt. A one-way engagement collar is mounted over an end portion of the sleeve. The one-way engagement collar is configured to rotate freely on the end portion of the sleeve when the sleeve rotates in a first direction and lock onto rotation of the sleeve when the sleeve rotates in a second direction. The one-way engagement collar further has a plurality of ramp pockets that extend axially in from an end surface of the one-way engagement collar. A ramp member is received within each ramp pocket of the plurality of ramp pockets in the one-way engagement collar. Each ramp member is configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of the belt when the sleeve rotates in the second direction.

In another embodiment, a drive sheave assembly of a continuously variable transmission is provided. The drive sheave assembly includes a post, a fixed sheave, a movable sheave, a sleeve, a one-way engagement collar, a plurality of pairs of locking rollers and roller biasing members, and ramp members. The fixed sheave is statically mounted on the fixed post. The fixed sheave includes a central recess. The fixed sheave further includes a plurality of sheave ramps within the central recess. The movable sheave is slidably mounted on the fixed post. The sleeve is rotatably mounted on the post. A mid-portion of the sleeve is positioned between the fixed sheave and the movable sheave. The mid-portion of the sleeve includes an outer surface configured engage an inner surface of a belt. The one-way engagement collar mounted over an end portion of the sleeve. The one-way engagement collar has a plurality of locking pockets extending axially in from a side edge of the one-way engagement collar. The one-way engagement collar including a plurality of roller windows. Each roller window extending radially from an inside surface of the one-way engagement collar into an associated locking pocket. The one-way engagement collar further having a plurality of ramp pockets that extend axially in from an end surface of the one-way engagement collar. Each pair of locking roller and roller biasing member of the plurality of the locking rollers and roller biasing members received in an associated locking pocket of the one-way engagement collar. A portion of each locking roller extends through an associated roller window of the one-way engagement collar to engage the portion of the sleeve. Each locking pocket and associated pair of locking roller and roller biasing member being configured to allow rotation of the one-way engagement collar on the end portion of the sleeve when the sleeve rotates in a first direction and lock rotation of the one-way engagement collar onto the rotation of the sleeve when the sleeve rotates in a second direction. The ramp member is received within each ramp pocket of the plurality of ramp pockets in the one-way engagement collar. Each ramp member is configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of the belt when the sleeve rotates in the second direction.

In yet another embodiment, a vehicle that includes a drivetrain, an engine, and a continuously variable transmission is provided. The continuously variable transmission is in operational communication between the drivetrain and the engine to couple torque between the engine and the drivetrain. The continuously variable transmission includes at least one sheave assembly. The at least one sheave assembly further includes a post a fixed sheave, a movable sheave, a sleeve, a one-way engagement collar, and ramp members. The fixed sheave is statically mounted on the fixed post. The fixed sheave includes a central recess. A plurality of sheave ramps are located within the central recess. The movable sheave is slidably mounted on the fixed post. The sleeve is rotatably mounted on the post. A mid-portion of the sleeve is positioned between the fixed sheave and the movable sheave. The mid-portion of the sleeve has an outer surface that is configured to engage an inner surface of a belt. The one-way engagement collar is mounted over an end portion of the sleeve. The one-way engagement collar is configured to rotate freely on the end portion of the sleeve when the sleeve rotates in a first direction and lock onto rotation of the sleeve when the sleeve rotates in a second direction. The one-way engagement collar further has a plurality of ramp pockets that extend axially in from an end surface of the one-way engagement collar. The ramp member is received within each ramp pocket of the plurality of ramp pockets in the one-way engagement collar. Each ramp member is configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of the belt when the sleeve rotates in the second direction.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments can be more easily understood and further advantages and uses thereof will be more readily apparent, when considered in view of the detailed description and the following figures in which:

FIG.1A is a side view of a drive sheave assembly of a CVT with an engine braking system in an inactivated configuration according to one exemplary embodiment;

FIG.1B is a side view of the drive sheave of a CVT ofFIG.1A with the engine braking system in an activated configuration according to one exemplary embodiment;

FIG.2 is an unassembled view of the drive sheave assembly ofFIG.1A;

FIG.3 is an end perspective view of a one-way engagement collar according to one exemplary embodiment;

FIG.4 is a side perspective view of a fixed sheave and the one-way engagement collar according to one exemplary embodiment;

FIG.5 is an end perspective view of a sleeve according to one exemplary embodiment;

FIG.6A is a cross-sectional side view of the drive sheave assembly ofFIG.1A with the engine braking system in the inactivated configuration;

FIG.6B is a close-up partial cross-sectional side view of the drive sheave assembly ofFIG.6A illustrating the engine braking system in the inactivated configuration;

FIG.7A is a cross-sectional side view of the drive sheave assembly ofFIG.1B with the engine braking system in the activated configuration;

FIG.7B is a close-up partial cross-sectional side view of the drive sheave assembly ofFIG.7A illustrating the engine braking system in the activated configuration;

FIG.8 is a block diagram of vehicle that includes the drive sheave assembly ofFIG.1A according to one exemplary embodiment;

FIG.9 is an unassembled side view of an engine braking system according to another exemplary embodiment; and

FIG.10 is an end view of the one-way engagement collar mounted on the sleeve in the engine braking system ofFIG.9.

In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the subject matter described. Reference characters denote like elements throughout Figures and text.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the inventions may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the claims and equivalents thereof.

Embodiments provide a CVT with an engine braking system (EBS) (CVT EBS) that implements a one-way engagement collar to selectively engage a portion of a belt during an engine braking situation to clamp down on the belt with an associated sheave assembly. Some embodiments are further configured to disengage the engine braking feature when a threshold is reached to protect vehicle components.

Referring toFIGS.1A and1B side views of adrive sheave assembly100 of a CVT EBS of an example embodiment is illustrated. Thedrive sheave assembly100 is part of a CVT such asCVT304 discussed below. The drive sheave assembly100 (or drive clutch assembly) includes a fixedsheave102 and amovable sheave104. Themovable sheave104 is configured to move axially in relation to the fixedsheave102 under control of a movablesheave activation assembly140. In one embodiment, the axial location of themovable sheave104 on a post of thedrive sheave assembly100 is based off centrifugal forces the drive sheave assembly is experiencing due to rotation of thedrive sheave assembly100. Thedrive sheave assembly100 includes a one-way engagement collar120 which is in a retracted configuration inFIG.1A.FIG.1B illustrates the one-way engagement collar120 in a belt engaging configuration which would occur during an engine braking situation.

An unassembled view of thedrive sheave assembly100 is illustrated inFIG.2. As illustrated, thedrive sheave assembly100 includes the fixed (or stationary) sheave102 that is statically mounted on apost110. Thedrive sheave assembly100 further includesseals112 and128, thrustwashers126 and130,bias members132 and136,spring cup134 andnut141. Further illustrated areramp members114, bullets116 (caps) andbias members118 that work with the one-way engagement collar120 to selectively activate (move axially) the one-way engagement collar120 to engage a belt200 (shown inFIG.7A) of the CVT. The movablesheave activation assembly140 includes amain bias member136.

FIG.3 illustrates a closeup side perspective view of the one-way engagement collar120,ramp members114,bullets116 and bullet bias members118 (springs). Eachramp member114 includes a rampedsurface114awhich extends between afirst end114bto aramp stop portion114dat asecond end114c. The one-way engagement collar120 is generally ring shaped with a central opening having afirst end surface120aandsecond end surface120b(best illustrated inFIG.2). The one-way engagement collar120 includes spaced ramp pockets121 that extend into thefirst end surface120aof the one-way engagement collar120. Eachramp member114 is received with an associatedend ramp pocket121 such that theramp surface114aof eachramp114 is facing outward from the one-way engagement collar120.

The one-way engagement collar120 further includes a plurality of bullet pockets123 that radially extend into the one-way engagement collar120 from aninterior surface120cof the one-way engagement collar120. Eachbullet116 andbullet bias member118 is received within an associatedbullet pocket123 in the one-way engagement collar120. The one-way engagement collar120 may further include a plurality of spacedvoids125, which in one example, is used to reduce the overall weight of the one-way engagement collar120.

FIG.4 illustrates that the fixedsheave102 includes acentral recess103 in this example embodiment. Within thecentral recess103 is located sheave ramps105. Eachsheave ramp105 is positioned to engage a rampedsurface114aof an associatedramp member114. The sheave ramp/ramp member arrangement is configured to selectively move the one-way engagement collar120 axially as discussed below in detail.FIG.4 also illustrates abullet116 received within an associatedbullet pocket123 in the one-way engagement collar120.

Referring toFIG.5, a close-up side view of thesleeve106 and how thebullets116 interact with the sleeve is illustrated. Thesleeve106 in one embodiment is an idler bearing that includesbearings107 that are position partially within aninner surface106bof thesleeve106 to engage thepost110. A mid-portion106eof thesleeve106 includes anouter surface106athat engages an inner surface of belt of the CVT (shown inFIG.6A). Anend portion106cof thesleeve106 includes asleeve ramp portion109 in this example. Aridge portion111 separates theend portion106cfrom the mid-portion106e. As illustrated inFIG.6A the mid-portion is positioned between the fixedsheave102 and themovable sheave104.

Thesleeve ramp portion109 includes a plurality of sleeve ramps109a, Each of the radially positionedsleeve ramp109aterminates with a sleeve ramp stop109cwhich starts thenext sleeve ramp109a, As illustrated, thebullets116, biased by the associatedbullet bias members118 that are received within bullet bores115 of thebullets116, ride along theramps109aof thesleeve ramp portion109. When thesleeve106 rotates in a first direction, thebullets116 simply ride over theramps109awith thebullet bias members118 forcing thebullets116 to engage the surfaces oframps109aeven as they pass over the sleeve ramp stops109c(i.e., they snap over the sleeve ramp stops109cwhen the sleeve rotates in the first direction). When thesleeve106 rotates in the other direction (second direction), such as when a drivetrain is overrunning the rotation provided by the engine, thebullets116 engaging the sleeve ramp stops109clock rotation of the one-way engagement collar120 (which houses the bullets116) with rotation of thesleeve106.

FIG.6A illustrates a cross-sectional side view of thedrive sheave assembly100. As illustrated, the movablesheave activation assembly140 in this embodiment includes themain bias member136, which in this embodiment is a compression spring, and a plurality offly weights142 and associatedstationary members144. Themain bias member136, positioned between thespring cup134 and a portion of the movablesheave activation assembly140, exerts a force on themovable sheave104 away from the fixedsheave102. This condition may occur at vehicle idle where thesleeve106 rotates freely on thepost110 in the first direction of thedrive sheave assembly100 and no torque if transferred to thebelt200. As the rotational speed of the drive sheave assembly increases, such as when a vehicle throttle is increases, thefly weights142 engaging thestationary members144 counter the main bias member force causing themovable sheave104 towards the fixedsheave102. This action results in thebelt200 being clamped between the fixed andmovable sheaves102 and104 therein coupling torque between thesheaves102 and104 and thebelt200. As the speed of the drive sheave assembly increases and decreases, the belt moves up and down engagement surfaces the fixed andmovable sheaves102 and104 therein changing gearing by changing the distance of thebelt200 from a central axis of thedrive sheave assembly100. Further, as the rotational speed of thedrive sheave assembly100 decreases the bias force from themain bias member136 overcomes the force of the flyweight/stationary member144 arrangement and the belt rides back down towards thesleeve106.

FIG.6A illustrates thedrive sheave assembly100 in an operating configuration where engine braking is not needed. This operating configuration may occur when a vehicle is idling while on relatively even terrain. In this configuration,belt200 has an inner surface that rides on theouter surface106aof thesleeve106. Only a portion of thebelt200 is illustrated inFIG.6A. Since thesleeve106 is free to rotate in a first direction in relation to thepost110, no torque from thedrive sheave assembly100 is coupled to thebelt200 in this idle configuration.

FIG.6B illustrates a close-up illustration of the engine braking assembly in the idle operation configuration. As illustrated, the one-way engagement collar120 is received within the central recess103 (or cavity) of the fixedsheave102 with thesecond end120b(orengaging end surface120b) of the one-way engagement collar120 being flush with a conical faced engagingsurface102aof the fixedsheave102. Since thesleeve106 is rotating in the first direction in this idle configuration, thebullets116 are sliding over the sleeve ramps109aof the sleeve ramp portion of thesleeve106 allow rotation between the one-way engagement collar120 and thesleeve106.

Also illustrated inFIG.6B is the position ofseal112 in a groove in a surface of thecentral recess103 of the fixedsheave102. In one example embodiment, theseal112 is an O-ring seal. Further in an embodiment, the seal is a quad ring seal. Also illustrated is the position ofseal128 in an inside groove in the inner surface of the one-way engagement collar120. In one embodiment the seal is a Teflon™ PTFE seal with or without an O-ring energizer. Theseals112 and128 are positioned to prevent debris, such as belt debris, from getting to the ramped features (bullet/sleeve ramp and ramp member/sheave ramp features). Also illustrated inFIG.6B is the positioning of bias member132 (engine braking bias member) between thethrust washer130 and another side of thespring cup134.Bias member132 in this embodiment is acompression wave spring132. The function ofbias member132 is to exert a force on the sleeve/one-way engagement collar assembly to retain the one-way engagement collar120 within thecentral recess103 of the fixedsheave102 when an engine braking condition is not present.

FIG.7A illustrates a side view of thedrive sheave assembly100 in an engine braking configuration. In this configuration, the one-way engagement collar120 moves out from thecentral recess103 of the fixedsheave102 to engage a side portion of thebelt200. This action causes the drive sheave assembly100 (the one-way engagement collar120 and the movable sheave104) to clamp down on thebelt200 therein coupling torque between a drivetrain of a vehicle and the engine to allow engine braking to occur.FIG.7B illustrates a close-up view of the engine braking assembly during the engine braking condition.

As discussed above, engine braking occurs when a vehicle's drivetrain causes thebelt200 to overrun the sleeve (move the sleeve in an opposite or second direction). This can occur, for example, when the vehicle is at idle while going down a steep hill. In this situation, thebelt200, which rides on the sleeve during idle, rotates thesleeve106 in an opposite direction (second rotational direction) from its normal direction (first rotational direction) provided by a rotational output of the engine. Rotation ofsleeve106 in the second direction causes thebullets116 in the one-way engagement collar120 to engage the sleeve ramp stops109con thesleeve ramp portion109 of thesleeve106 therein locking rotation of the one-way engagement collar120 with rotation of thesleeve106. This causes eachramp member114 housed within the ramp pockets121 of the one-way engagement collar to move in relation to the ramp members associatedsheave ramp105 in thecentral recess103 of the fixedsheave102 therein moving the one-way engagement collar out of thecentral recess103 to engage thebelt200. This clamps thebelt200 between an engagement surface of the one-way engagement collar120 and an engagement surface of themoveable sheave104 therein coupling torque between thedrive sheave assembly100 and thebelt200.

One feature of the engine braking assembly is that the function of the engine braking can be disconnected under certain conditions even when the drivetrain is overrunning thesleeve106. This may be desired to protect the vehicle components during extreme conditions. This feature is accomplished with the configuration of the one-way feature in the one-way engagement collar120. Thebullet bias members118 within the cavity of thebullets116 may be selected to exert a select mount of bias force to engage the sleeve ramps109aand sleeve ramp stops109cof thesleeve ramp portion109 of thesleeve106. The bias force may be selected so that a predetermined amount of centrifugal force caused by rotation of one-way engagement collar120 counters the bias force provided by thebullet bias members118. This causes thebullets116 to move back into their associated bullet pockets123 in the one-way engagement collar120. When this happens, thebullets116 no longer engage the sleeve ramp stops109cof the sleeve ramps109aof thesleeve106. The one-way engagement collar120 is then again free to rotate in relation to thesleeve106. This allows eachramp member114 housed within the ramp pockets121 of the one-way engagement collar120 to move in relation to the ramp members associatedsheave ramp105 in thecentral recess103 of the fixedsheave102 aided by bias member132 (which may be a wave spring) therein moving the one-way engagement collar into thecentral recess103 away from thebelt200. Once the centrifugal force lessens, the bias force from thebullet bias members118 overcomes the centrifugal force and thebullets116 once again extend out from there associated bullet pockets123 to engage the sleeve ramp stops109cto enact the engine braking by axially moving the one-way engagement collar120 to engage a portion of thebelt200.

Referring to block diagram ofFIG.8, anexample vehicle300 implementing adrive sheave assembly100 is illustrated. Thedrive sheave assembly100 is part of aCVT304 that further includes the belt200 (or endless looped member) and a drivensheave assembly306. Thedrive sheave assembly100 is in operational communication with anengine302. The drivensheave assembly306 is in operational communication with thedrive sheave assembly100 via thebelt200 to selectively communicate torque between thedrive sheave assembly100 and the drivensheave assembly306.

The drivensheave assembly306 is in communication with the drivetrain that, in this example, includes agear box308, a front andrear drive shaft310 and312 (or prop shafts), front andrear differentials314 and316,front half shafts318aand318b,rear half shafts322aand322b,front wheels320aand320bandrear wheels324aand324b.

As discussed above, an engine braking system that includes the one-way engagement collar120 is activated when torque from the drivetrain communicated through the drivensheave assembly306 andbelt200 to thedrive sheave assembly100 tries to overrun the sleeve106 (move the sleeve in the second direction). This may occur when theengine302 is at idle while thevehicle300 is traveling down a hill. This overrunning of thesleeve106 causes thebullets116, within the bullet pockets123 of the one-way engaging collar120, to engage the sleeve ramp stops109cof thesleeve106 therein locking rotation of the one-way engagement collar120 with thesleeve106. As the one-way engagement collar120 is overrunning (rotating with the sleeve106), theramp members114 in the ramp pockets121 slide on the sheave ramps105 which axially moves the one-way engagement collar120 to engage a side portion of thebelt200. This causes thedrive sheave assembly100 to clamp down on thebelt200 coupling torque between the belt and theengine302 to the enable engine braking. When thebelt200 is no longer overrunning the sleeve106 (rotating in the second direction), which will occur when the engine revolutions increase or when the terrain pitch the vehicle is encountering has been reduced, the engine braking system is disengaged. Further, as discussed above, the engine braking system may be designed to disengage when an overrunning torque reaches a predefined threshold to protect components of thevehicle300. Although,FIG.8 illustrates a continuously variable transmission engine braking system being used in a vehicle with wheels, other types of vehicles using a CVT such as, but not limited, vehicles that use one or more tracks may implement the continuously variable transmission engine braking system.

FIGS.9 and10 illustrates yet another example embodiment of anengine braking system400 that would be included in adrive sheave assembly100 of aCVT304 as discussed above. This example embodiment includes asleeve406. The sleeve includes anouter surface406athat is designed to engage in inner surface of a belt, such asbelt200 discussed above and aninner surface406b. Aridge portion406dextends from theouter surface406aof thesleeve406 that separates theouter surface406adesigned to engage thebelt200 and anend portion406cof thesleeve406 designed to engage an inner surface of a one-way engagement collar412. In this embodiment, theend portion406cdoes not include ramps. The outer surface of theend portion406cis a smooth surface with a consistent diameter.

The one-way engagement collar412 in this example, includes a plurality of lockingpockets411 extending axially in anend surface412aof the one-way engagement collar412. Each lockingpocket411 is configured to receive a lockingroller416 and associated compression spring418 (roller biasing member418). Each lockingpocket411 includes aroller window411athat allows a portion of an associatedlocking roller416 to engage the endouter surface406cof thesleeve406. The configuration of each lockingpocket411 with its associatedlocking roller416 andcompression spring418 allows the one-way engagement collar412 to rotate freely in relation to thesleeve406 in a first direction while locking rotation of the one-way engagement collar412 with thesleeve406 in a second direction (which would occur in during an engine braking situation). In particular, a cam profile in each lockingpocket411 prevents the lockingroller416 from rotating as it is wedged between the cam profile in its associated lockingpocket411 and the endouter surface406cof thesleeve406 during an engine braking situation.Retainer plates422 andfasteners424 are used in this example to retain the lockingrollers416 and compression springs418 within their associated locking pockets411 in the one-way engagement collar412.

The one-way engagement collar412 in this example also includes ramp pockets413 that are configured to receiveramp members420. Likeramp members114 discussed above. Theramp members420 are configured to engagesheave ramps105 located within acentral recess103 of a fixedsheave102. When the one-way engagement collar412 locks rotation with thesleeve406 in an engage braking situation, theramp members420/engagesheave ramps105 move the one-way engagement collar412 to engage a side of the belt to enhance engine braking.

Theengine braking system400 further includes alip seal407 to keep grease retained inside a bearing of thesleeve406 as wells asseals408 and414 and thrust washer410.Seal414 is positioned between an outer surface of the one-way engagement collar412 and an interior surface of the central recess of the fixed sleeve in an example embodiment.

EXAMPLE EMBODIMENTS

Example 1 includes a drive sheave assembly of a continuously variable transmission, the drive sheave assembly includes a post, a fixed sheave, a movable sheave, a sleeve, a one-way engagement collar and ramp members. The fixed sheave is statically mounted on the fixed post and includes a central recess. The fixed sheave further includes a plurality of sheave ramps within the central recess. The movable sheave is slidably mounted on the fixed post. The sleeve is rotatably mounted on the post. A mid-portion of the sleeve is positioned between the fixed sheave and the movable sheave and has an outer surface configured to engage an inner surface of a belt. A one-way engagement collar is mounted over an end portion of the sleeve. The one-way engagement collar is configured to rotate freely on the end portion of the sleeve when the sleeve rotates in a first direction and lock onto rotation of the sleeve when the sleeve rotates in a second direction. The one-way engagement collar further has a plurality of ramp pockets that extend axially in from an end surface of the one-way engagement collar. A ramp member is received within each ramp pocket of the plurality of ramp pockets in the one-way engagement collar. Each ramp member is configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of the belt when the sleeve rotates in the second direction.

Example 2 includes the drive sheave assembly of Example 1, further wherein the one-way engagement collar further has a plurality of locking pockets extending axially in from the end surface of the one-way engagement collar. The one-way engagement collar includes a plurality of roller windows. Each roller window extends radially from an inside surface of the one-way engagement collar into an associated locking pocket. A plurality of pairs of locking rollers and roller biasing members are received in an associated locking pocket of the one-way engagement collar. A portion of each locking roller extends through an associated roller window of the one-way engagement collar to engage the end portion of the sleeve. Each locking pocket and associated pair of locking roller and roller biasing member are configured to rotate freely on the end portion of the sleeve when the sleeve rotates in the first direction and lock onto rotation of the sleeve when the sleeve rotates in the second direction.

Example 3 includes the drive sheave assembly of Example 2, further including a plurality or retainer plates and fasteners. Each retaining plate and at least one associated fastener of the plurality or retainer plates and fasteners are configured to cover an associated locking pocket to retain an associated pair of locking roller and roller biasing member within the associated locking pocket.

Example 4 includes the drive sheave assembly of Example 1, further wherein the end portion of the sleeve includes a plurality of sleeve ramps. Each sleeve ramp terminates with a ramp sleeve stop. The one-way engagement collar has a plurality of bullet pockets that extend radially in from an interior surface of the one-way engagement collar.

Example 5 includes the drive sheave assembly of Example 4, further including a plurality of bullets. Each bullet includes a bore. Each bullet further configured to be received within an associated bullet pocket of the plurality of bullet pockets in the one-way engagement collar. A bullet bias member is received in each bore of each bullet to provide a bias force an associated bullet of the plurality of bullets to engage an associated sleeve ramp and ramp sleeve stop of the plurality of the sleeve ramps of the sleeve ramp portions of the sleeve.

Example 6 includes the drive sheave assembly of Example 5, wherein the bullet bias members are configured to provide a select amount of force that can be countered by a defined centrifugal force provided by a rotation rate of the one-way engagement collar.

Example 7 includes the drive sheave assembly of any of the Examples 1-6, further including at least one seal positioned between the sleeve and the one-way engagement collar.

Example 8 includes the drive sheave assembly of any of the Examples 1-7, further including at least one seal positioned between the fixed sheave and the one-way engagement collar.

Example 9 includes the drive sheave assembly of any of the Examples 1-8, further including an engine braking bias member configured to exert an axial force on the one-way engagement member into central recess of the fixed sheave.

Example 10 includes the drive sheave assembly of any of the Examples 1-9, further including an engine braking system that is configured to disengage the one-way engagement collar from the belt when a centrifugal force threshold is reached during an engine braking condition.

Example 11 includes the drive sheave assembly of any of the Examples 1-10, wherein the one-way engagement collar is configured to be received within the central recess of the fixed sheave during non-engine braking conditions and to extend at least partially out of the central recess to engage the side of the belt during an engine braking condition.

Example 12 includes a drive sheave assembly of a continuously variable transmission, the drive sheave assembly includes a post, a fixed sheave, a movable sheave, a sleeve, a one-way engagement collar, a plurality of pairs of locking rollers and roller biasing members, and ramp members. The fixed sheave is statically mounted on the fixed post. The fixed sheave includes a central recess. The fixed sheave further includes a plurality of sheave ramps within the central recess. The movable sheave is slidably mounted on the fixed post. The sleeve is rotatably mounted on the post. A mid-portion of the sleeve is positioned between the fixed sheave and the movable sheave. The mid-portion of the sleeve includes an outer surface configured engage an inner surface of a belt. The one-way engagement collar mounted over an end portion of the sleeve. The one-way engagement collar has a plurality of locking pockets extending axially in from a side edge of the one-way engagement collar. The one-way engagement collar including a plurality of roller windows. Each roller window extending radially from an inside surface of the one-way engagement collar into an associated locking pocket. The one-way engagement collar further having a plurality of ramp pockets that extend axially in from an end surface of the one-way engagement collar. Each pair of locking roller and roller biasing member of the plurality of the locking rollers and roller biasing members received in an associated locking pocket of the one-way engagement collar. A portion of each locking roller extends through an associated roller window of the one-way engagement collar to engage the portion of the sleeve. Each locking pocket and associated pair of locking roller and roller biasing member being configured to allow rotation of the one-way engagement collar on the end portion of the sleeve when the sleeve rotates in a first direction and lock rotation of the one-way engagement collar onto the rotation of the sleeve when the sleeve rotates in a second direction. The ramp member is received within each ramp pocket of the plurality of ramp pockets in the one-way engagement collar. Each ramp member is configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of the belt when the sleeve rotates in the second direction.

Example 13 includes the drive sheave assembly of Example 12, further including a plurality or retainer plates and fasteners. Each retaining plate and at least one associated fastener of the plurality or retainer plates and fasteners are configured to cover an associated locking pocket to retain an associated pair of locking roller and roller biasing member within the associated locking pocket.

Example 14 includes the drive sheave assembly of any of the Examples 12-13, wherein the one-way engagement collar is configured to be received within the central recess of the fixed sheave during non-engine braking conditions and to extend at least partially out of the central recess to engage the side of the belt during an engine braking condition.

Example 15 includes the drive sheave assembly of any of the Examples 12-14, wherein each ramp pocket of the plurality of the ramp pockets includes a cam profile that allows for the rotation of the one-way engagement collar on the end portion of the sleeve when the sleeve rotates in the first direction while locking rotation of the one-way engagement collar onto the rotation of the sleeve when the sleeve rotates in the second direction.

Example 16 includes a vehicle that includes a drivetrain, an engine, and a continuously variable transmission. The continuously variable transmission is in operational communication between the drivetrain and the engine to couple torque between the engine and the drivetrain. The continuously variable transmission includes at least one sheave assembly. The at least one sheave assembly further includes a post a fixed sheave, a movable sheave, a sleeve, a one-way engagement collar, and ramp members. The fixed sheave is statically mounted on the fixed post. The fixed sheave includes a central recess. A plurality of sheave ramps are located within the central recess. The movable sheave is slidably mounted on the fixed post. The sleeve is rotatably mounted on the post. A mid-portion of the sleeve is positioned between the fixed sheave and the movable sheave. The mid-portion of the sleeve has an outer surface that is configured to engage an inner surface of a belt. The one-way engagement collar is mounted over an end portion of the sleeve. The one-way engagement collar is configured to rotate freely on the end portion of the sleeve when the sleeve rotates in a first direction and lock onto rotation of the sleeve when the sleeve rotates in a second direction. The one-way engagement collar further has a plurality of ramp pockets that extend axially in from an end surface of the one-way engagement collar. The ramp member is received within each ramp pocket of the plurality of ramp pockets in the one-way engagement collar. Each ramp member is configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of the belt when the sleeve rotates in the second direction.

Example 17 includes the vehicle of Example 16, wherein the at least one sheave assembly further wherein the one-way engagement collar further has a plurality of locking pockets extending axially in from the end surface of the one-way engagement collar. The one-way engagement collar includes a plurality of roller windows. Each roller window extends radially from an inside surface of the one-way engagement collar into an associated locking pocket. A plurality of pairs of locking rollers and roller biasing members are included. Each pair of locking roller and roller biasing member of the plurality of the locking rollers and roller biasing members are received in an associated locking pocket of the one-way engagement collar. A portion of each locking roller extends through an associated roller window of the one-way engagement collar to engage the end portion of the sleeve. Each locking pocket and associated pair of locking roller and roller biasing member are configured to rotate freely on the end portion of the sleeve when the sleeve rotates in a first direction and lock onto rotation of the sleeve when the sleeve rotates in a second direction.

Example 18 includes the vehicle of any of the Examples 16-17, further including a plurality or retainer plates and fasteners. Each retaining plate and at least one associated fastener of the plurality or retainer plates and fasteners configured to cover an associated locking pocket to retain an associated pair of locking roller and roller biasing member within the associated locking pocket.

Example 19 includes the vehicle of Examples 16 wherein the end portion of the sleeve of at least one sheave assembly further includes a plurality of sleeve ramps. Each sleeve ramp terminating with a ramp sleeve stop. The one-way engagement collar has a plurality of bullet pockets that extend radially in from an interior surface of the one-way engagement collar.

Example 20 includes the vehicle of Example 19, wherein the at least one sheave assembly further includes a plurality of bullets. Each bullet includes a bore. Each bullet is further configured to be received within an associated bullet pocket of the plurality of bullet pockets in the one-way engagement collar. A bullet bias member is received in each bore of each bullet to provide a bias force on an associated bullet of the plurality of bullets to engage an associated sleeve ramp and ramp sleeve stop of the plurality of the sleeve ramps of the sleeve ramp portions of the sleeve.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.

Claims (20)

The invention claimed is:

1. A drive sheave assembly of a continuously variable transmission, the drive sheave assembly comprising:

a post;

a fixed sheave statically mounted on the post, the fixed sheave including a central recess, the fixed sheave further including a plurality of sheave ramps within the central recess;

a movable sheave slidably mounted on the post;

a sleeve rotatably mounted on the post, a mid-portion of the sleeve positioned between the fixed sheave and the movable sheave, the mid-portion of the sleeve having an outer surface configured to engage an inner surface of a belt;

a one-way engagement collar mounted over an end portion of the sleeve, the one-way engagement collar configured to rotate freely on the end portion of the sleeve when the sleeve rotates in a first direction and lock onto rotation of the sleeve when the sleeve rotates in a second direction, the one-way engagement collar further having a plurality of ramp pockets that extend axially in from an end surface of the one-way engagement collar; and

a ramp member received within each ramp pocket of the plurality of ramp pockets in the one-way engagement collar, each ramp member configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of the belt when the sleeve rotates in the second direction.

2. The drive sheave assembly ofclaim 1, further wherein:

the one-way engagement collar further having a plurality of locking pockets extending axially in from the end surface of the one-way engagement collar, the one-way engagement collar including a plurality of roller windows, each roller window extending radially from an inside surface of the one-way engagement collar into an associated locking pocket; and

a plurality of pairs of locking rollers and roller biasing members, each pair of locking roller and roller biasing member of the plurality of the locking rollers and roller biasing members received in an associated locking pocket of the one-way engagement collar wherein a portion of each locking roller extends through an associated roller window of the one-way engagement collar to engage the end portion of the sleeve, each locking pocket and associated pair of locking roller and roller biasing member being configured to rotate freely on the end portion of the sleeve when the sleeve rotates in the first direction and lock onto rotation of the sleeve when the sleeve rotates in the second direction.

3. The drive sheave assembly ofclaim 2, further comprising:

a plurality or retainer plates and fasteners, each retaining plate and at least one associated fastener of the plurality or retainer plates and fasteners configured to cover an associated locking pocket to retain an associated pair of locking roller and roller biasing member within the associated locking pocket.

4. The drive sheave assembly ofclaim 1, further wherein:

the end portion of the sleeve including a plurality of sleeve ramps, each sleeve ramp terminating with a ramp sleeve stop; and

the one-way engagement collar having a plurality of bullet pockets that extend radially in from an interior surface of the one-way engagement collar.

5. The drive sheave assembly ofclaim 4, further comprising:

a plurality of bullets, each bullet including a bore, each bullet further configured to be received within an associated bullet pocket of the plurality of bullet pockets in the one-way engagement collar; and

a bullet bias member received in each bore of each bullet to provide a bias force an associated bullet of the plurality of bullets to engage an associated sleeve ramp and ramp sleeve stop of the plurality of the sleeve ramps of the sleeve ramp portions of the sleeve.

6. The drive sheave assembly ofclaim 5, wherein the bullet bias members are configured to provide a select amount of force that can be countered by a defined centrifugal force provided by a rotation rate of the one-way engagement collar.

7. The drive sheave assembly ofclaim 1, further comprising:

at least one seal positioned between the sleeve and the one-way engagement collar.

8. The drive sheave assembly ofclaim 1, further comprising:

at least one seal positioned between the fixed sheave and the one-way engagement collar.

9. The drive sheave assembly ofclaim 1, further comprising:

an engine braking bias member configured to exert an axial force on the one-way engagement member into central recess of the fixed sheave.

10. The drive sheave assembly ofclaim 9, further comprising:

an engine braking system configured to disengage the one-way engagement collar from the belt when a centrifugal force threshold is reached during an engine braking condition.

11. The drive sheave assembly ofclaim 1, wherein the one-way engagement collar is configured to be received within the central recess of the fixed sheave during non-engine braking conditions and to extend at least partially out of the central recess to engage the side of the belt during an engine braking condition.

12. A drive sheave assembly of a continuously variable transmission, the drive sheave assembly comprising:

a post;

a fixed sheave statically mounted on the post, the fixed sheave including a central recess, the fixed sheave further including a plurality of sheave ramps within the central recess;

a movable sheave slidably mounted on the post;

a sleeve rotatably mounted on the post, a mid-portion of the sleeve positioned between the fixed sheave and the movable sheave, the mid-portion of the sleeve including an outer surface configured engage an inner surface of a belt;

a one-way engagement collar mounted over an end portion of the sleeve, the one-way engagement collar having a plurality of locking pockets extending axially in from a side edge of the one-way engagement collar, the one-way engagement collar including a plurality of roller windows, each roller window extending radially from an inside surface of the one-way engagement collar into an associated locking pocket, the one-way engagement collar further having a plurality of ramp pockets that extend axially in from an end surface of the one-way engagement collar;

a plurality of pairs of locking rollers and roller biasing members, each pair of locking roller and roller biasing member of the plurality of the locking rollers and roller biasing members received in an associated locking pocket of the one-way engagement collar wherein a portion of each locking roller extends through an associated roller window of the one-way engagement collar to engage the portion of the sleeve, each locking pocket and associated pair of locking roller and roller biasing member being configured to allow rotation of the one-way engagement collar on the end portion of the sleeve when the sleeve rotates in a first direction and lock rotation of the one-way engagement collar onto the rotation of the sleeve when the sleeve rotates in a second direction; and

a ramp member received within each ramp pocket of the plurality of ramp pockets in the one-way engagement collar, each ramp member configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of the belt when the sleeve rotates in the second direction.

13. The drive sheave assembly ofclaim 12, further comprising:

a plurality or retainer plates and fasteners, each retaining plate and at least one associated fastener of the plurality or retainer plates and fasteners configured to cover an associated locking pocket to retain an associated pair of locking roller and roller biasing member within the associated locking pocket.

14. The drive sheave assembly ofclaim 12, wherein the one-way engagement collar is configured to be received within the central recess of the fixed sheave during non-engine braking conditions and to extend at least partially out of the central recess to engage the side of the belt during an engine braking condition.

15. The drive sheave assembly ofclaim 12, wherein each ramp pocket of the plurality of the ramp pockets includes a cam profile that allows for the rotation of the one-way engagement collar on the end portion of the sleeve when the sleeve rotates in the first direction while locking rotation of the one-way engagement collar onto the rotation of the sleeve when the sleeve rotates in the second direction.

16. A vehicle comprising:

a drivetrain;

an engine; and

a continuously variable transmission in operational communication between the drivetrain and the engine to couple torque between the engine and the drivetrain, the continuously variable transmission including at least one sheave assembly, the at least one sheave assembly further including,

a post,

a fixed sheave statically mounted on the post, the fixed sheave including a central recess, the fixed sheave further including a plurality of sheave ramps within the central recess;

a movable sheave slidably mounted on the post,

a sleeve rotatably mounted on the post, a mid-portion of the sleeve positioned between the fixed sheave and the movable sheave, the mid-portion of the sleeve having an outer surface configured to engage an inner surface of a belt,

a one-way engagement collar mounted over an end portion of the sleeve, the one-way engagement collar configured to rotate freely on the end portion of the sleeve when the sleeve rotates in a first direction and lock onto rotation of the sleeve when the sleeve rotates in a second direction, the one-way engagement collar further having a plurality of ramp pockets that extend axially in from an end surface of the one-way engagement collar, and

a ramp member received within each ramp pocket of the plurality of ramp pockets in the one-way engagement collar, each ramp member configured to engage an associated sheave ramp of the plurality of sheave ramps in the central recess of the fixed sheave and move the one-way engagement collar axially to engage a side of the belt when the sleeve rotates in the second direction.

17. The vehicle ofclaim 16, wherein the at least one sheave assembly further comprising:

the one-way engagement collar further having a plurality of locking pockets extending axially in from the end surface of the one-way engagement collar, the one-way engagement collar including a plurality of roller windows, each roller window extending radially from an inside surface of the one-way engagement collar into an associated locking pocket; and

a plurality of pairs of locking rollers and roller biasing members, each pair of locking roller and roller biasing member of the plurality of the locking rollers and roller biasing members received in an associated locking pocket of the one-way engagement collar wherein a portion of each locking roller extends through an associated roller window of the one-way engagement collar to engage the end portion of the sleeve, each locking pocket and associated pair of locking roller and roller biasing member being configured to rotate freely on the end portion of the sleeve when the sleeve rotates in a first direction and lock onto rotation of the sleeve when the sleeve rotates in a second direction.

18. The vehicle ofclaim 16, wherein the at least one sheave assembly further comprising:

a plurality or retainer plates and fasteners, each retaining plate and at least one associated fastener of the plurality or retainer plates and fasteners configured to cover an associated locking pocket to retain an associated pair of locking roller and roller biasing member within the associated locking pocket.

19. The vehicle ofclaim 16, wherein the at least one sheave assembly further comprising:

the end portion of the sleeve including a plurality of sleeve ramps, each sleeve ramp terminating with a ramp sleeve stop; and

the one-way engagement collar having a plurality of bullet pockets that extend radially in from an interior surface of the one-way engagement collar.

20. The vehicle ofclaim 16, wherein the at least one sheave assembly further comprising:

a plurality of bullets, each bullet including a bore, each bullet further configured to be received within an associated bullet pocket of the plurality of bullet pockets in the one-way engagement collar; and

a bullet bias member received in each bore of each bullet to provide a bias force on an associated bullet of the plurality of bullets to engage an associated sleeve ramp and ramp sleeve stop of the plurality of the sleeve ramps of the sleeve ramp portions of the sleeve.

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